数据未显示在数据库的列表视图中。它说数据库中没有任何内容

Question

我已经通过arraylist在我的数据库中插入数据，但它没有显示在数据库中。这是我的代码

 public void fillData(){
    // code to add the new Question
    SQLiteDatabase db= this.getWritableDatabase();

    //now i am making some questions model
    Question_Activity_Model model =new Question_Activity_Model("whcih girl of our class can sing song?","xyz","Mehak tariq","abc","Alina",1,"A");
    //this is one model object now i am saving it in our list first
    DataCollection.get(context).fillQuestionsList(model);
     model =new Question_Activity_Model("whcih girl of our class can sing song?","xyz","Mehak tariq","abc","Alina",1,"A");
    DataCollection.get(context).fillQuestionsList(model);
    //now two model objects are saved in arraylist..
///now i am getting data from arraylist
    for (Question_Activity_Model questn: DataCollection.get(context).getQuestionsList()) {
        //now i am getting all the models from the list and looping them one by one to get model object..i am using forech for looping..
        ContentValues values= new ContentValues();
        values.put(QuestId,questn.getId());
        values.put(Quests,questn.getQuestion());
        values.put(Option1,questn.getOption1());
        values.put(Option2,questn.getOption2());
        values.put(Option3,questn.getOption3());
        values.put(Option4,questn.getOption4());
        values.put(CorrectOption,questn.getCorrectoption());
       db.insert("QuestionsTable", null, values);
        db.close();
    }

此代码位于扩展sqlite open helper class

的数据库类中

- 这段代码在我的主要活动类

中

public class Question_activity_main extends AppCompatActivity {
    ListView listView;

    Question_Activity_Model qm;
    AppDatabase appDatabase;
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.question_activity_main);

        listView = (ListView) findViewById(R.id.queslistView);
        appDatabase= new AppDatabase(this);
        ArrayList<Question_Activity_Model> question_activity_modelArrayList = new ArrayList<>();
        Cursor c= appDatabase.retrieveQuests();
        if (c.getCount()==0){
            Toast.makeText(getApplicationContext(), "Nothing in db", Toast.LENGTH_SHORT).show();
        }
        else {
           while (c.moveToNext()){
               question_activity_modelArrayList.add(qm );
            Question_Activity_Adapter question_activity_adapter= new Question_Activity_Adapter(this, question_activity_modelArrayList );
               listView.setAdapter(question_activity_adapter);
           }

        }

这是我的Question_Activity_Adapter

的代码

  public class Question_Activity_Adapter extends BaseAdapter {
    private Activity activity;
    private ArrayList<Question_Activity_Model> question_activity_modelArrayList;
    private LayoutInflater inflater;

    public Question_Activity_Adapter(Activity activity, ArrayList<Question_Activity_Model> question_activity_modelArrayList) {
        this.activity = activity;
        this.question_activity_modelArrayList = question_activity_modelArrayList;
        this.inflater = activity.getLayoutInflater();
    }

    @Override
    public int getCount() {
        return question_activity_modelArrayList.size();
    }

    @Override
    public Object getItem(int position) {
        return question_activity_modelArrayList.get(position);
    }

    @Override
    public long getItemId(int i) {
        return i;
    }

    @Override
    public View getView(int i, View view, ViewGroup viewGroup) {
        View v= view;
        if (v== null){
            v= inflater.inflate(R.layout.questions_activity, null);

        }
        RadioGroup radioGroup= (RadioGroup) v.findViewById(R.id.radiogroup);
        TextView questionTextView= (TextView) v.findViewById(R.id.textView2);
        final RadioButton radioButton2= (RadioButton) v.findViewById(R.id.radioButton2);
        final RadioButton radioButton3= (RadioButton) v.findViewById(R.id.radioButton3);
        final RadioButton radioButton4= (RadioButton) v.findViewById(R.id.radioButton4);
        final RadioButton radioButton5= (RadioButton) v.findViewById(R.id.radioButton5);
        Question_Activity_Model question_activity_model= (Question_Activity_Model) getItem(i);
        String question= question_activity_model.getQuestion();
        questionTextView.setText(question);
        final String option1= question_activity_model.getOption1();
        radioButton2.setText(option1);
        String option2= question_activity_model.getOption2();
        radioButton3.setText(option2);
        String option3= question_activity_model.getOption3();
        radioButton4.setText(option3);
        String option4= question_activity_model.getOption4();
        radioButton5.setText(option4);
        radioGroup.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(RadioGroup radioGroup, int i) {
                if (radioButton2.isChecked()){
                    radioButton3.setEnabled(!isEnabled(i));
                    radioButton4.setEnabled(!isEnabled(i));
                    radioButton5.setEnabled(!isEnabled(i));
                }
                if (radioButton3.isChecked()){
                    radioButton2.setEnabled(!isEnabled(i));
                    radioButton4.setEnabled(!isEnabled(i));
                    radioButton5.setEnabled(!isEnabled(i));
                }
                if (radioButton4.isChecked()){
                    radioButton2.setEnabled(!isEnabled(i));
                    radioButton3.setEnabled(!isEnabled(i));
                    radioButton5.setEnabled(!isEnabled(i));
                }
                if (radioButton5.isChecked()){
                    radioButton2.setEnabled(!isEnabled(i));
                    radioButton3.setEnabled(!isEnabled(i));
                    radioButton4.setEnabled(!isEnabled(i));
                }
            }
        });
        return v;
    }   
}